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Re: [Xen-devel] Interrupt issue for nic cards

To: Wei Liu <liuw@xxxxxxxxx>
Subject: Re: [Xen-devel] Interrupt issue for nic cards
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Fri, 13 May 2011 09:39:31 -0400
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
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On Fri, May 13, 2011 at 11:14:47AM +0800, Wei Liu wrote:
> Hi, all.
> I'm running the latest Xen unstable with Debian Squeeze as DomU in HVM mode.
> I configured two nics:
> vif = ['bridge=br0,model=virtio', 'type=ioemu,bridge=br0,model=rtl8139']
> These two cards can be successfully configured in DomU. But they fail
> to communicate with host bridge.
> I can see packets coming out their taps, but no packets are going back
> into DomU.
> Stefano suggest I look into /proc/interrupts. It shows:
> 11      0    IO-APIC-fasteoi   eth0
> 48      0    PCI-MSI-edge   virtio0-config
> 49      0    PCI-MSI-edge   virtio0-input
> 50      0    PCI-MSI-edge   virtio0-output
> It seems that there are no interrupts for those nic devices. I'm
> pretty sure that QEMU has pushed the data back and set interrupts
> (through msix_notify / qemu_set_irq).
> Has anyone encountered this problem before?

I haven't. But it looks like the NIC isn't beeing interrupted - which
implies that QEMU hasn't sent the IRQ to the DomU to tell it: 'hey
you got data'. It might be worth looking in QEMU and see under which
circumstances it sends interrupts. And whether the mechanism for sending
interrupts is KVM specific instead of being more generic (or able to
use the Xen mechanism).

> -- 
> Best regards
> Wei Liu
> Twitter: @iliuw
> Site: http://liuw.name
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel

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